Process for the preparation of sodium-silicate solution



W 19251 c. D. WOOD 1.719.038

mobmss FOR Tm:- PREPARATION OF SODIUM SILICATE SOLUTION Filed May 26,1927 4o tion of the desired concentration. This excess Patented 2,litlfi ll hi l l3.

stares PATENT FFICE.

mma-m Lilihtlllfi li WCl'tlltl, 0F ULEVE'DAND, 'OH LL'U, ASSIGNOR, BYMESNE ASSIGNMENTS; T0 GRASQELLI GEEMIGAL COMPANY, OF CLEVELAND, OHIO, ACORPORATION 01' P3067 253 THE PREPARATION OF SODIUlI-STLICATE SOLUTION.

, Application filed May 26,

The roduction of aqueous solution of sodium siiicate from sodiumsilicate glass preseats a number of diiiiculties which have made itimpractical for small consumers to prepare their own solutions. Sodiumsilicate, therefore, usually is marketed in the form of its solutions,as a result of which freight rates are a vital factor in its cost to theconsumers.

The usual grades of. sodium silicate glass do not dissolve in water aseasily as ordinary inorganic salts, such as sodium chloride or sodiumsulfate, or organic products, such as cane sugar. As a matter of fact,if lumps of sodium silicate lass are boiled in water, they do not seemto issolve at all.

When sodium silicate glass in lump form is treated with water and steamunder pressure in stationary boilers provided with false bottoms, oropen work baskets, it happens quite often, particularly when theconditions of temperature, steam pressure, time, etc, are not maintainedunder proper close control, that the lumps a glomerate into sticky orgummy masses whic dissolve only very slowly or not atall. A gelatinouscoating, which itself is insoluble, forms on the lumps causing them toagglomerate and effectively preventing the water from reaching theinterior of the lumps.

Circulation of the liquor and even agitation, is well nigh impossible insuch dissolvers due to the high viscosity of the silicate solution andto the formation of such ummy, sticky masses, which are usually cal edstickers.

The dissolvers, moreover, due to the lack of agitation, contain strataof solution of different concentrations which prevent accurate samplingand determination of the average concentration. It has always beencustomary to carry in the dissolvers a surplus of glass to hastendissolving and the production of soluof glass, however, gives rise tovariations of concentration in the successive batches of solutionproduced unless the concentration is carefully checked by frequent testsand controlled.

I have now devised a simple and inexpensive methodrequiring no highlyskilled opera 'tion or so ervision whereby sodium silicate glass of a 1commercial grades is easily dissolved in water to the production ofsolutions of predetermined concentration.

My method or process consists essentially in introducin a charge ofsodium silicate glass prefera ly in the form of relatively 1927. SerialNo. 194,488.

said pressure until the silicate is dissolved.

The charge then may be blown from the cyllnder under its own pressureinto the bottom of a storage tank, from which the solution is drawn offas required. Incidental to the development of the method, I have devisedan apparatus suitable for carrying out the method, the construction andoperation of which will be described in connection with the accompanyingdrawings in which the fi ure is a vertical elevation of the rotarycylind er and its associated mechanism.

Referring to the drawing, der 1 has a charging hole 2, a vent 3, and avalved outlet 4 and is mounted on bearings 5 and 6 to be rotated bymeans of the motor 7 acting through the universal joint 8, speed reducer9 and gears 10 and 11 at a rate of, for instance, 5 to 10 revolutions erminute. 12 is a bearing for the power sha 13. Bearings 5 and 6 arecarried b suitable supports 14.- and 15, the whole assem ly beingmounted on the frame 16 which may be provided with wheels or rollerssoas to be easily portable. The pipe 17 communicates with the interior ofthe cylinder 1 through the hollow shaft 18 and t rough the check valve19 and flexible joint 20 with the valved water supply line 21 and steamga e 22 and thence through the valve 23 with t e safety valve 24,pressure regulator 25 and steam supply line 26. The cylinder 1preferably is provided with bafiie plates (not shown), for instance,three equally spaced plates extending the entire length of t e cylinder,to promote the agitation of the contents. The cylinder may be of ansuitable size, say about 4. feet Ion and a out 4 feet-in diameter andmade 0 any suitable materialfi-A suitable operating pressure is about 60pounds pressure per square inch. The operation of the apparatus isobvious from the foregoing description.

Assuming that the water glass and water are charged into the cylinder inproportions within the range of the solubility ofthe silicate which mayinclude solutions of concentrations ordinarily used in trade, thesilicate the rotary cylinsolv is ra idly and practically completely dis-08 leaving no residue in the c linder and eliminating t e prior practicere erred to of an excess of silicate. Consequently,

vnsm'gb each atch of silicate solution may, by roper to the thorou hagitation which occurs in .the cylinder t ere 18 no stratification ofthe solution such as occurs in the prior process referred to. In makingsilicate solution of a predetermined concentration from a .uniformsupply of silicate glass all conditions may be standardized includingeven the time required for operation upon each batch. The exactoperating conditions will of course vary to some extent depending uponthe roperties of the silicate lass, for instance its alkalinity the sizeof t e lumps, the concentration oi solution to be prepared, the

- pressure employed inthe cylinder and even to some extent upon theshape and size of the v cylinder and atmospheric conditions, but

practically all of these conditions may be standardized and homogeneoussolutions of redetermined concentration in successive atches roduced.The amount of steam condensed in the cylinder must be taken into accountbut this factor may be eliminated by heating the cylinder, for instance,by means of a steam jacket, instead of by injecting steam into thecylinder.

In a typical 0 construction an sizedescribed involving the ration inapparatus of the use oi about 1400 pounds of sodium silicate glass, 1770(pounds of water, steam of poun s and revolving the cylinder at the rateof 5 to 10 revolutions per minute requires about 90 minutes operation topr uce complete solution of the silicate.

As stated above the prom is adapted to be carried out in batch operationin a relatively small dissolving apparatus which ma portable and theresulting batches of silicate solution may be delivered under their ownpressure into a stor e vessel. The stor vessel preferabl is o sufiicientsize to ho d a' pluralit of atches of the solution produced in t edissolver, and the solution preferably is introduced into the storagevessel near the bottom so that its entrance under the pressure in thedissolver produces agitation-and mixing of the contents of the storagevessel. In this way any variation in the composition of succeedingbatches of solution produced in the dissolvor may be largely equalizedand the solution in the storage vessel is maintained at a uniform andhomoeneou's composition. A portable dissolving apparatus obviously mzyadvantage ously be used to an ply a plur ity of storage vessels atseparate points in a manufacturing plant.

claim:

Process for the production of sodium silicate solution from sodiumsilicate glass, which comprises agitating successive batches of amixture of sodium silicate glass and water under superatmospheric steampressure and at a corresponding tem rature in a closed rotary cylinderuntil t e glass is ressure substantially completely dissolved and de- Ilivering the successive batches of the resulting sodium silicatesolution from .said cylinder by the force of said pressure into thebottom of a storage vessel capable of holding a plurality of saidbatches.

In testimony whereof, I aflix my signature.

' CHARLES D. WOOD.

